Conventional snowthrowers generally include a wheel supported body or frame having a drive means for rotating an auger or impeller located within a fixed housing including a pair of opposing side walls, a top wall and a rear wall, which cooperate to define a downwardly and forwardly projecting snow-receiving opening. Snow is introduced into the housing by operation of the auger and then expelled therefrom through a chute connected to the top wall of the housing.
In the absence of the provision of a drive train between the drive means of a conventional snowthrower and its supporting wheels, it is normally necessary for an operator to constantly grip a handle assembly and apply constant manual forward force to push the snowthrower forward. With regard to such snowthrowers, it has been recognized, as for example in U.S. Pat. Nos. 2,587,415 and 4,694,594, that the rotating auger may be used as a temporary drive mechanism for propelling the snowthrower over obstructions, but this requires the operator to lift the handle assembly in order to rotate or tilt the complete snowthrower forward sufficiently to place the rotating auger in engagement with the ground. While this technique may be temporarily used to propel the snowthrower over unyielding obstructions or irregular terrain, it is not suitable for constant normal use. First, in this respect, forward tilting of the snowthrower tends to create a wide gap between the ground and the bottom of the rear wall of the housing through which snow, ice, stones, etc. may be thrown from the interior of the housing back toward the operator, endangering the operator and leaving a vast, unwanted trail of snow. Second, the operator is in great danger of walking into and inadvertently placing a foot through the exposed wide gap and into the rotating auger when lifting the handle assembly. Third, the operator is susceptible to muscle fatigue from constantly lifting the handle assembly and snowthrower to engage the auger with the ground for extended periods.